CN117501178A - Method and apparatus for particle beam induced processing of defects in microlithographic photomasks - Google Patents
Method and apparatus for particle beam induced processing of defects in microlithographic photomasks Download PDFInfo
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- CN117501178A CN117501178A CN202280042961.1A CN202280042961A CN117501178A CN 117501178 A CN117501178 A CN 117501178A CN 202280042961 A CN202280042961 A CN 202280042961A CN 117501178 A CN117501178 A CN 117501178A
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- 238000000034 method Methods 0.000 title claims abstract description 177
- 230000007547 defect Effects 0.000 title claims abstract description 176
- 239000002245 particle Substances 0.000 title claims abstract description 84
- 238000012545 processing Methods 0.000 title claims abstract description 44
- 230000008439 repair process Effects 0.000 claims abstract description 187
- 230000008569 process Effects 0.000 claims abstract description 88
- 241000820057 Ithone Species 0.000 claims abstract 2
- 238000012360 testing method Methods 0.000 claims description 66
- 238000005530 etching Methods 0.000 claims description 37
- 239000000463 material Substances 0.000 claims description 27
- 238000000151 deposition Methods 0.000 claims description 16
- 230000008021 deposition Effects 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 13
- 230000003213 activating effect Effects 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 10
- 238000001393 microlithography Methods 0.000 claims description 10
- 238000004590 computer program Methods 0.000 claims description 7
- 238000006073 displacement reaction Methods 0.000 claims description 4
- FGUUSXIOTUKUDN-IBGZPJMESA-N C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 Chemical compound C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 FGUUSXIOTUKUDN-IBGZPJMESA-N 0.000 claims description 3
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- WTEOIRVLGSZEPR-UHFFFAOYSA-N boron trifluoride Chemical compound FB(F)F WTEOIRVLGSZEPR-UHFFFAOYSA-N 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 230000001419 dependent effect Effects 0.000 description 4
- 230000006870 function Effects 0.000 description 4
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- 238000005286 illumination Methods 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- -1 diaryl chromium Chemical compound 0.000 description 3
- 238000001900 extreme ultraviolet lithography Methods 0.000 description 3
- 238000001459 lithography Methods 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 239000011733 molybdenum Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 238000007493 shaping process Methods 0.000 description 3
- BLIQUJLAJXRXSG-UHFFFAOYSA-N 1-benzyl-3-(trifluoromethyl)pyrrolidin-1-ium-3-carboxylate Chemical compound C1C(C(=O)O)(C(F)(F)F)CCN1CC1=CC=CC=C1 BLIQUJLAJXRXSG-UHFFFAOYSA-N 0.000 description 2
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910015900 BF3 Inorganic materials 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 2
- 238000002679 ablation Methods 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- WYTGDNHDOZPMIW-RCBQFDQVSA-N alstonine Natural products C1=CC2=C3C=CC=CC3=NC2=C2N1C[C@H]1[C@H](C)OC=C(C(=O)OC)[C@H]1C2 WYTGDNHDOZPMIW-RCBQFDQVSA-N 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
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- 238000004364 calculation method Methods 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- KTWOOEGAPBSYNW-UHFFFAOYSA-N ferrocene Chemical compound [Fe+2].C=1C=C[CH-]C=1.C=1C=C[CH-]C=1 KTWOOEGAPBSYNW-UHFFFAOYSA-N 0.000 description 2
- 239000005350 fused silica glass Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000010884 ion-beam technique Methods 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- OHZZTXYKLXZFSZ-UHFFFAOYSA-I manganese(3+) 5,10,15-tris(1-methylpyridin-1-ium-4-yl)-20-(1-methylpyridin-4-ylidene)porphyrin-22-ide pentachloride Chemical compound [Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[Mn+3].C1=CN(C)C=CC1=C1C(C=C2)=NC2=C(C=2C=C[N+](C)=CC=2)C([N-]2)=CC=C2C(C=2C=C[N+](C)=CC=2)=C(C=C2)N=C2C(C=2C=C[N+](C)=CC=2)=C2N=C1C=C2 OHZZTXYKLXZFSZ-UHFFFAOYSA-I 0.000 description 2
- WKFBZNUBXWCCHG-UHFFFAOYSA-N phosphorus trifluoride Chemical compound FP(F)F WKFBZNUBXWCCHG-UHFFFAOYSA-N 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000001454 recorded image Methods 0.000 description 2
- 239000005049 silicon tetrachloride Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 230000008685 targeting Effects 0.000 description 2
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 2
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 description 2
- NXHILIPIEUBEPD-UHFFFAOYSA-H tungsten hexafluoride Chemical compound F[W](F)(F)(F)(F)F NXHILIPIEUBEPD-UHFFFAOYSA-H 0.000 description 2
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 1
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- YGBYJRVGNBVTCQ-UHFFFAOYSA-N C[Pt](C)C.[CH]1C=CC=C1 Chemical compound C[Pt](C)C.[CH]1C=CC=C1 YGBYJRVGNBVTCQ-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- CPELXLSAUQHCOX-UHFFFAOYSA-N Hydrogen bromide Chemical compound Br CPELXLSAUQHCOX-UHFFFAOYSA-N 0.000 description 1
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 1
- 206010024769 Local reaction Diseases 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 229910052794 bromium Inorganic materials 0.000 description 1
- WNCWUCSNEKCAAI-UHFFFAOYSA-N carbanide;2-methylcyclopenta-1,3-diene;platinum(4+) Chemical compound [CH3-].[CH3-].[CH3-].[Pt+4].CC1=[C-]CC=C1 WNCWUCSNEKCAAI-UHFFFAOYSA-N 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- NQZFAUXPNWSLBI-UHFFFAOYSA-N carbon monoxide;ruthenium Chemical group [Ru].[Ru].[Ru].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-] NQZFAUXPNWSLBI-UHFFFAOYSA-N 0.000 description 1
- FQNHWXHRAUXLFU-UHFFFAOYSA-N carbon monoxide;tungsten Chemical group [W].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-].[O+]#[C-] FQNHWXHRAUXLFU-UHFFFAOYSA-N 0.000 description 1
- 150000001728 carbonyl compounds Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 150000001845 chromium compounds Chemical class 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- ZDICFBIJLKDJAQ-UHFFFAOYSA-N dichloroxenon Chemical compound Cl[Xe]Cl ZDICFBIJLKDJAQ-UHFFFAOYSA-N 0.000 description 1
- 125000000118 dimethyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 description 1
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- 238000011419 induction treatment Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- OCVXZQOKBHXGRU-UHFFFAOYSA-N iodine(1+) Chemical compound [I+] OCVXZQOKBHXGRU-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- VPCDQGACGWYTMC-UHFFFAOYSA-N nitrosyl chloride Chemical compound ClN=O VPCDQGACGWYTMC-UHFFFAOYSA-N 0.000 description 1
- 239000001272 nitrous oxide Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- UHZYTMXLRWXGPK-UHFFFAOYSA-N phosphorus pentachloride Chemical compound ClP(Cl)(Cl)(Cl)Cl UHZYTMXLRWXGPK-UHFFFAOYSA-N 0.000 description 1
- FAIAAWCVCHQXDN-UHFFFAOYSA-N phosphorus trichloride Chemical compound ClP(Cl)Cl FAIAAWCVCHQXDN-UHFFFAOYSA-N 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 150000003482 tantalum compounds Chemical class 0.000 description 1
- YPLOYFASLUPKHY-UHFFFAOYSA-N tetrachloroxenon Chemical compound [Xe](Cl)(Cl)(Cl)Cl YPLOYFASLUPKHY-UHFFFAOYSA-N 0.000 description 1
- VXKWYPOMXBVZSJ-UHFFFAOYSA-N tetramethyltin Chemical compound C[Sn](C)(C)C VXKWYPOMXBVZSJ-UHFFFAOYSA-N 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- XCZXGTMEAKBVPV-UHFFFAOYSA-N trimethylgallium Chemical compound C[Ga](C)C XCZXGTMEAKBVPV-UHFFFAOYSA-N 0.000 description 1
- KPGXUAIFQMJJFB-UHFFFAOYSA-H tungsten hexachloride Chemical compound Cl[W](Cl)(Cl)(Cl)(Cl)Cl KPGXUAIFQMJJFB-UHFFFAOYSA-H 0.000 description 1
- 230000005641 tunneling Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
- G03F1/76—Patterning of masks by imaging
- G03F1/78—Patterning of masks by imaging by charged particle beam [CPB], e.g. electron beam patterning of masks
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
- G03F1/72—Repair or correction of mask defects
- G03F1/74—Repair or correction of mask defects by charged particle beam [CPB], e.g. focused ion beam
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
- G03F1/72—Repair or correction of mask defects
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
- G03F1/80—Etching
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/0002—Inspection of images, e.g. flaw detection
- G06T7/0004—Industrial image inspection
- G06T7/0006—Industrial image inspection using a design-rule based approach
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/10—Segmentation; Edge detection
- G06T7/136—Segmentation; Edge detection involving thresholding
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/60—Analysis of geometric attributes
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/10—Image acquisition modality
- G06T2207/10056—Microscopic image
- G06T2207/10061—Microscopic image from scanning electron microscope
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/30—Subject of image; Context of image processing
- G06T2207/30108—Industrial image inspection
- G06T2207/30148—Semiconductor; IC; Wafer
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Theoretical Computer Science (AREA)
- Plasma & Fusion (AREA)
- Quality & Reliability (AREA)
- Geometry (AREA)
- Preparing Plates And Mask In Photomechanical Process (AREA)
Abstract
A method for particle beam induced processing of defects (D, D') of a microlithographic photomask (100), comprising the steps of: a) Providing (S1) an image (300) of at least a portion of the photomask (100); b) Determining (S2) whether the geometry of the defect (D, D ') in the image (300) is a repair shape (302, 302 '), the repair shape (302, 302 ') comprising n pixels (304); c) Subdividing (S3) the repair shape (302, 302') into k sub-repair shapes (306) in a computer-implemented manner, an ith one of the k sub-repair shapes (306) having m i -a number of pixels (304) which is a subset of the n pixels (304) of the repair shape (302, 302'); d) For the purpose of processing the first sub-repair shape (306), m in the first sub-repair shape (306) i Each of the pixels (304)Providing (S4) an activated particle beam (202) and a process gas; e) Repeating (S5) step d) for a first sub-repair shape (306) for j repetition periods; and f) repeating (S6) steps d) and e) for each other sub-repair shape (306).
Description
Technical Field
The present invention relates to a method and apparatus for particle beam induced processing of defects in microlithographic photomasks.
Background
Microlithography is used to produce microstructured components such as integrated circuits. A microlithography process is performed using a lithographic apparatus having an illumination system and a projection system. In this case, an image of a photomask (reticle) illuminated by an illumination system is projected by a projection system onto a substrate, for example a silicon wafer, which is coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system in order to transfer the mask structure onto the photosensitive coating of the substrate.
In order to obtain smaller structure dimensions and thus to increase the integration density of the microstructure components, light with very short wavelengths, for example known as Deep Ultraviolet (DUV) or Extreme Ultraviolet (EUV), is increasingly used. The wavelength of DUV is, for example, 193nm and the wavelength of EUV is, for example, 13.5nm.
In this case, the microlithography photomask has a structure size ranging from a few nanometers to hundreds of nanometers. The production of such photomasks is very complex and therefore costly. In particular, this is the case because the photomask must be defect free, otherwise it is impossible to ensure that the structures produced on the silicon wafer by the photomask exhibit the desired functions. In particular, the quality of the structures on the photomask is decisive for the quality of the integrated circuits produced on the wafer by means of said photomask.
For this reason, microlithography photomasks are inspected for defects and the defects found are repaired in a targeted manner. Typical defects include lack of envisaged structures, for example because the etching process was not successfully performed, or the presence of non-envisaged structures, for example because the etching process proceeds too fast or produces its effect at the wrong location. These defects can be remedied by targeted etching of excess material or targeted deposition of additional material in place; this can be achieved in a very targeted manner, for example, by means of an electron beam induction process (FEBIP, "focused electron beam induction process").
DE 10 2017 208 114 A1 describes a method for particle beam induced etching of photolithographic masks. In this case, a particle beam (in particular an electron beam) and an etching gas are provided at the locations on the lithography mask to be etched. The particle beam activates a local chemical reaction between the activated material and the etching gas, as a result of which the material is ablated locally from the lithography mask.
It has been determined that for large area defects, the composition of the supplied process gas (e.g., etching gas) may change adversely as the size of the defect increases. This can seriously impair the handling of the defect. For example, the etch rate may be significantly reduced due to the unfavorable gas composition, so that defects cannot be completely removed, or can only be completely removed with a higher electron beam dose (that is, for example, with a longer etch duration).
Disclosure of Invention
Against this background, it is an object of the present invention to provide an improved method and an improved apparatus for particle beam induced processing of defects of microlithographic photomasks.
Accordingly, a method for particle beam induced processing of defects of a microlithographic photomask is proposed. The method comprises the following steps:
a) Providing an image of at least a portion of the photomask;
b) Determining whether the geometry of the defect in the image is a repair shape, the repair shape comprising n pixels;
c) Subdividing the repair shape into k sub-repair shapes in a computer-implemented manner, an ith of the k sub-repair shapes having mi pixels, the mi pixels being a subset of n pixels of the repair shape;
d) Providing an activating particle beam and a process gas at each of the mi pixels of the first sub-repair shape for the purpose of processing the first sub-repair shape;
e) Repeating step d) for a first sub-repair shape for j repetition periods; and
f) Repeating steps d) and e) for each additional sub-repair shape.
In particular, n, k, m i Each of j is an integer greater than or equal to 2. Further, i is an integer designating a counter from 1 to k.
The repair shape is subdivided into a plurality of sub-repair shapes, so that the processing time of one of the sub-repair shapes is shorter than the processing time of the entire repair shape. As a result, the gas composition of the process gas required and/or optimal for treating the defect can be better ensured during the treatment of the sub-repair shape. As a result, defects can be handled better. For example, the proposed method makes it possible to also treat large-area repair shapes and/or repair shapes with many pixels with an advantageous and/or optimal gas composition of the process gas.
The processing of the defects includes, inter alia, etching of the defects, partial ablation of material from the photomask within its scope, or deposition of material on the photomask in the areas of the defects. For example, the proposed method allows for better etching away of unwanted structures in the defect area or may better add missing structures in the defect area.
An image of at least a portion of the photomask is recorded, for example, by a Scanning Electron Microscope (SEM). For example, the image of at least a portion of the photomask is of the order of a few nanometers in spatial resolution. Images may also be recorded using a Scanning Probe Microscope (SPM), such as an Atomic Force Microscope (AFM) or a Scanning Tunneling Microscope (STM).
The method may particularly comprise the step of capturing an image of at least a portion of the photomask by means of a scanning electron microscope and/or a scanning probe microscope.
For example, a microlithography photomask is a photomask for an EUV lithography apparatus. In this case EUV stands for "extreme ultraviolet" and means that the wavelength of the working light is between 0.1nm and 30nm, in particular 13.5nm. In EUV lithography apparatuses, a beam shaping and illumination system is used to direct EUV radiation onto a photomask (also referred to as a "reticle"), in particular in the form of a reflective optical element (reflective photomask). A photomask has a structure that is imaged onto a wafer or the like in a reduced manner by a projection system of an EUV lithographic apparatus.
For example, the microlithography photomask may also be a photomask for a DUV lithographic apparatus. In this case, DUV stands for "deep ultraviolet" and means that the wavelength of the working light is between 30nm and 250nm, in particular 193nm or 248nm. In DUV lithographic apparatus, the beam shaping and illumination system is used to direct DUV radiation onto a photomask, in particular in the form of a transmissive optical element (transmissive photomask). A photomask has structures that are imaged onto a wafer or the like in a demagnified fashion by the projection system of the DUV lithographic apparatus.
For example, a microlithography photomask includes a substrate and a structure formed on the substrate by a coating. For example, the photomask is a transmissive photomask, in which case the pattern to be imaged is realized in the form of an absorbing (i.e., opaque or partially opaque) coating on a transparent substrate. Alternatively, the photomask may also be a reflective photomask, for example, particularly for use in EUV lithography.
For example, the substrate comprises silicon dioxide (SiO 2 ) Such as fused silica. For example, the structured coating comprises chromium, chromium compounds, tantalum compounds, and/or compounds made from silicon, nitrogen, oxygen, and/or molybdenum. The substrate and/or coating may also comprise other materials.
In the case of a photomask for an EUV lithographic apparatus, the substrate may comprise an alternating sequence (sequence) of molybdenum and silicon layers.
Using the proposed method, defects of a photomask, in particular defects of a structured coating of the photomask, can be identified, located and repaired. In particular, the defect is a (e.g., absorbing or reflecting) coating of the photomask that is incorrectly applied to the substrate. The method may be used to add coating to a photomask at locations where the coating is absent. In addition, the method may be used to remove the coating from the photomask where the coating was improperly applied.
For this purpose, the geometry of the defect is determined in the recorded image of at least a portion of the photomask. For example, a two-dimensional geometry of the defect is determined. The geometry of the determined defect is hereinafter referred to as the so-called repair shape.
N pixels are defined in the repair shape for particle beam induced processing of the repair shape. During steps d) to f) of the method, the particle beam is directed towards each of the n pixels of the repair shape. In particular, the intensity maximum of the electron beam is directed toward each center of each of the n pixels. In other words, the n pixels of the repair shape represent a grating of the repair shape for the particle beam induced processing, in particular a two-dimensional grating. For example, n pixels of the repair shape correspond to an incident area of the particle beam during the particle beam induction process of the defect. For example, the pixel size is selected in such a way that: due to the gaussian intensity distribution of the electron beam, the intensity distribution of the electron beam directed towards the center of the pixel drops to a predetermined intensity at the edges of said pixel. The predetermined intensity may correspond to a decrease to half of the intensity maximum, or to any other fraction of the intensity maximum of the electron beam. For example, the pixel size and/or the electron beam full width at half maximum (full width at half maximum) are in the sub-nanometer range or on the order of a few nanometers.
For example, the process gas is a precursor (pre) gas and/or an etching gas. For example, the process gas may be a mixture of a plurality of gas components, i.e., a process gas mixture. For example, the process gas may be a mixture of a plurality of gas components, wherein each gas component has only a specific molecular type.
In particular, alkyl compounds of main group elements, metals or transition elements may be considered suitable precursor gases for deposition or growth lifting structures. An example thereof is (cyclopentadienyl) trimethylplatinum (CpPtMe) 3 Me＝CH 4 ) (methylcyclopentadienyl) trimethylplatinum (MeCpPtMe 3 ) Tetramethyl tin (SnMe) 4 ) Trimethylgallium (GaMe) 3 ) Ferrocene (Cp) 2 Fe), diaryl chromium (Ar) 2 Cr), and/or carbonyl compounds of main group elements, metals or transition elements, such as, for example, chromium hexacarbonyl (Cr (CO) 6 ) Molybdenum hexacarbonyl (Mo (CO) 6 ) Tungsten hexacarbonyl (W (CO) 6 ) Cobalt octacarbonyl (Co 2 (CO)) 8 ) Triruthenium dodecacarbonyl (Ru) 3 (CO) 12 ) Iron pentacarbonyl (Fe (CO) 5 ) And/or alkoxide compounds of main group elements, metals or transition elements, such as, for example, tetraethoxysilane (Si (OC) 2 H 5 ) 4 ) Titanium tetraisopropoxide (Ti (OC) 3 H 7 ) 4 ) And/or halides of main group elements, metals or transition elements, such as, for example, tungsten hexafluoride (WF) 6 ) Tungsten hexachloride (WCl) 6 ) Titanium tetrachloride (TiCl) 4 ) Boron trifluoride (BF) 3 ) Silicon tetrachloride (SiCl) 4 ) And/or complexes comprising main group elements, metals or transition elements, such as, for example, copper bis (hexafluoroacetylacetonate) (Cu (C) 5 F 6 HO 2 ) 2 ) Trifluoroacetylacetonate dimethyl (Me) 2 Au(C 5 F 3 H 4 O 2 ) And/or organic compounds, e.g. carbon monoxide (CO), carbon dioxide (CO) 2 ) Aliphatic and/or aromatic hydrocarbons, and the like.
For example, the etching gas may include: xenon difluoride (XeF) 2 ) Xenon dichloride (XeCl) 2 ) Xenon tetrachloride (XeCl) 4 ) Steam (H) 2 O), heavy water (D 2 O), oxygen (O) 2 ) Ozone (O) 3 ) Ammonia (NH) 3 ) Nitrous chloride (NOCl) and/or one of the following halides: XNO, XONO 2 、X 2 O、XO 2 、X 2 O 2 、X 2 O 4 、X 2 O 6 Wherein X is a halide. Other etching gases for etching one or more deposited test structures are described in detail in applicant's U.S. patent application No. 13/0103281.
The process gas may contain further additive gases, for example oxidizing gases, such as hydrogen peroxide (H 2 O 2 ) One (one)Nitrous oxide (N) 2 O), nitric Oxide (NO), nitrogen dioxide (NO 2 ) Nitric acid (HNO) 3 ) And other oxygen-containing gases and/or halides, such as chlorine (Cl) 2 ) Hydrogen chloride (HCl), hydrogen Fluoride (HF), iodine (I) 2 ) Hydrogen Iodide (HI), bromine (Br) 2 ) Hydrogen bromide (HBr), phosphorus trichloride (PCl) 3 ) Phosphorus pentachloride (PCl) 5 ) Phosphorus trifluoride (PF) 3 ) Other halogen-containing gases and/or reducing gases, such as hydrogen (H) 2 ) Ammonia (NH) 3 ) Methane (CH) 4 ) And other hydrogen-containing gases. The additive gas may be used, for example, in etching processes, as a buffer gas, as a passivation medium, etc.
For example, the activated particle beam is provided by means of a device, which may comprise: a particle beam source for generating a particle beam; a particle beam directing device (e.g., a scanning unit) configured to direct a particle beam towards a pixel m of a corresponding sub-repair shape of the photomask i A place; a particle beam shaping device (e.g., an electron or beam optics assembly) configured to shape the particle beam, in particular, a focused particle beam; at least one storage vessel configured to store a process gas or at least a gas component of a process gas; at least one gas supply device configured to repair the shaped pixels m to the corresponding sub- i A process gas or at least a gas component of a process gas having a predetermined gas mass flow rate is provided.
For example, the activated particle beam comprises an electron beam, an ion beam, and/or a laser beam.
For example, the electron beam is provided by means of a modified scanning electron microscope. For example, an image of at least a portion of a photomask is recorded using a scanning electron microscope that provides the same modification of an activating electron beam.
The activating particle beam activates, in particular, a local chemical reaction between the photomask material and the process gas, which results in a local deposition of material on the photomask from the gas phase or a local transformation of the material of the photomask into the gas phase.
M in the corresponding sub-repair shape, e.g. by particle beam directing means i The active particle beam is provided consecutively at each of the pixels. In the methodIn step d) of (2), the activated particle beam is at m i A predetermined dwell time is maintained on each of the pixels. For example, the dwell time is 100ns.
In particular, steps d) to f) are performed uninterruptedly in a single repair sequence (sequence). That is, the particle beam is provided at the first pixel of the next sub-repair shape to be processed, in particular after having been provided at the last pixel of the first (or another) sub-repair shape.
According to one embodiment, m of the shape is repaired in step d) at the first sub-step i The active particle beam and the process gas are provided separately at each of the pixels.
In other words, the activating particle beam and the process gas are provided in step d) only at the pixels of the first sub-repair shape and not at the pixels of the further sub-repair shape. It can also be said that the sub-repair shape is continuously processed in steps d) to f).
According to a further embodiment, the repair shape is subdivided in step c) into k sub-repair shapes based on a threshold value.
For example, the repair shape is subdivided into a plurality of sub-repair shapes such that the sub-repair shapes all have the same size and the same number of pixels m i . For example, the repair shape may also be subdivided into a plurality of sub-repair shapes such that the number of pixels of the sub-repair shape, m i Less than 30%, 20%, 10%, 5%, 3% and/or 1% from each other.
For example, the repair shape is subdivided into a plurality of sub-repair shapes based on the threshold, such that a decision is made based on the threshold whether to perform step c). In other words, the repair shape is subdivided into a plurality of sub-repair shapes based on the threshold, for example, such that subdivision into a plurality of sub-repair shapes is performed if more than the threshold, while no repair shape is subdivided below the threshold.
For example, the repair shape is subdivided into a plurality of sub-repair shapes such that k sub-repair shapes into which the repair shape is subdivided are determined based on the threshold.
The threshold may also comprise a first (e.g., upper limit) and a second (e.g., lower limit) threshold (i.e., parameter range).
According to another embodiment, the threshold is an empirically determined value determined prior to step a).
Thus, the threshold may be defined before applying the method for particle beam induced processing of defects. For example, the threshold value may be predetermined and determined by the manufacturer of the apparatus for performing the method within the scope of a separate method for determining the threshold value. Thus, the method for handling photomask defects can be more easily performed by a user.
According to another embodiment, the particle beam induced processing includes etching of the defect or deposition of material on the defect, and the threshold value is determined based on an empirical value of the etch rate or deposition rate for the number of pixels n of the repair shape.
Accordingly, in the case of a defect corresponding to a photomask having a repair shape of n pixels, it is possible to ensure that a desired etching rate or deposition rate is obtained.
According to another embodiment, the threshold is an empirically determined value, which is determined based on a parameter selected from the group comprising: the number of pixels n of the repair shape, the size of the pixels, the incidence area of the particle beam, the dwell time of the activated particle beam on the respective pixels, the gas volume flow rate at which the process gas is supplied, the composition of the process gas, and the gas volume flow rate ratio of the various gas components of the process gas.
This may ensure that, in particular, the repair shape is subdivided into a plurality of sub-repair shapes in this way and that whenever such a subdivision is missing, the composition, the gas quantity and/or the density of the process gas at the pixels of the repair shape to be processed is disadvantageous when a certain pixel should be processed.
In particular, the threshold is an empirically determined threshold, which is determined in such a way that: defects of the photomask may be repaired (e.g., etched) to at least a predetermined quality by a particle beam induced process. For example, the quality of the repair is determined by determining the smoothness of the repair location (e.g., the smoothness of the etch), the width of the repair edge (e.g., the etched edge), the speed of the repair (e.g., the etch), and/or the etch rate or deposition rate.
In particular, the gas mass flow rate is a volumetric flow rate or flow rate that specifies the volume of process gas transferred per unit time through a defined cross section (e.g., a valve of a gas supply unit). For example, the gas mass flow rate is defined by setting the temperature of the process gas. For example, the temperature of the process gas is set in a temperature range between-40 ℃ and +20 ℃.
The dwell time is for the purpose of inducing a local reaction (chemical reaction, etching reaction and/or material deposition reaction) at the photomask at the location of this pixel, directing an activating particle beam towards m of the sub-repair shape i The duration of one of the pixels.
According to another embodiment, the repair shape is subdivided into a plurality of sub-repair shapes by means of a Voronoi method.
The Voronoi method or Voronoi diagram helps to easily subdivide the geometry of the defect (i.e., the repair shape) into sub-repair shapes. In particular, defects having irregular shapes and thus repair shapes having irregular shapes can be easily decomposed into sub-repair shapes.
According to another embodiment, in step c), the sub-repair shape is determined as a Voronoi region starting from the Voronoi center. Each sub-repair shape contains pixels of the repair shape corresponding to the associated Voronoi center, and all pixels of the repair shape that are disposed closer to the associated Voronoi center than any other Voronoi center of the repair shape.
In particular, the distance between Voronoi centers is predetermined based on the threshold in step c), and the Voronoi centers are determined based on the predetermined distance. For example, therefore, voronoi centers are defined in the repair shape such that they are uniformly distributed over the repair shape.
According to a further embodiment, the repair shape is subdivided into a plurality of sub-repair shapes, such that m of the respective sub-repair shape i The pixels have the same distance from each other in the scanning direction.
For example, the repair shape is a two-dimensional geometry defining an XY plane. For example, n pixels of the repair shape are arranged in the X-direction and the Y-direction. For example, the particle beam is directed in the X-direction and the Y-direction by means of a particle beam directing device (scanning unit). For example, the scanning direction corresponds to the X-direction and/or the Y-direction.
The situation avoided by pixels of the respective sub-repair shapes having the same distance from each other in the scanning direction is that during scanning the particle beam needs to be directed across a gap in the sub-repair shape, i.e. a region outside the sub-repair shape, when processing the sub-repair shape.
According to another embodiment, the repair shape comprises at least two spaced apart regions. Furthermore, the repair shape is subdivided into a plurality of sub-repair shapes such that each sub-repair shape comprises at most one of the at least two spaced apart regions.
Thus, during the processing of the sub-repair shape, the particle beam may be prevented from having to move back and forth between the non-contiguous regions, that is to say between the spaced-apart regions. This is particularly advantageous because the sub-repair shape is processed by the particle beam over j repetition periods, which may be of the order of 100, 1000, 10000, 100000 or 100 tens of thousands.
According to another embodiment, the method comprises the following steps before step d): calculating m in the first sub-repair shape i The sequence of activated particle beams is provided consecutively at the individual pixels such that the consumption of process gas by the chemical reaction activated by the activated particle beams is achieved uniformly over the sub-repair shape.
In particular, m for sub-repair shapes can be avoided i Progressive scanning of individual pixels.
According to another embodiment, the order in which steps d) and e) are performed in step f) for the further sub-repair shapes is different from the row-by-row and/or column-by-column order and/or random distribution.
In particular, the order in which the sub-repair shapes are processed by steps d) and e) is different from the row-by-row and/or column-by-column order and/or random distribution.
According to another embodiment, in step c), the repair shape is subdivided into sub-repair shapes in h mutually different subdivisions. Furthermore, steps d) to f) are performed for each of the h subdivisions (312, 316).
This can avoid defect handling non-uniformity at the boundaries between sub-repair shapes. In this case, h is an integer greater than or equal to 2.
For example, all h subdivided first sub-repair shapes may overlap each other, all h subdivided second sub-repair shapes may overlap each other, and so on. That is, for i=1 to k, all h subdivided i-th sub-repair shapes may overlap each other.
According to another embodiment, steps d) to f) are performed on g repetition periods for each of the h subdivisions, wherein g is smaller than j, and/or on j/h repetition periods.
Thus, the total number j of repeated cycles may be subdivided among h subdivisions. In this case, g is an integer greater than or equal to 2.
According to another embodiment, the h subdivisions differ from each other by the displacement, in particular the lateral displacement, of their boundaries of the repair shape relative to the repair shape.
In this way, the calculation of the further subdivision of the repair shape can be particularly easily achieved.
According to another embodiment, steps d) to f) are repeated for p repetition periods, wherein p is an integer greater than or equal to 2.
Since the defect is not completely repaired but only partially repaired during one iteration of steps d) to f), and the complete repair of the defect is achieved by only p repetition periods, non-uniformity of defect handling at the boundary between sub-repaired shapes can be avoided. This embodiment represents an alternative to using h mutually different subdivisions, or may be applied additionally.
According to another aspect, an apparatus for particle beam induced processing of defects of a microlithographic photomask is presented. The device comprises:
Means for providing an image of at least a portion of the photomask,
computing means for determining a geometry of the defect in the image as to whether the repair shape comprises n pixels, and the computing means is configured to subdivide the repair shape into a plurality of sub-repair shapes in a computer-implemented manner; and
Means for providing an activating particle beam and a process gas at each pixel of each sub-repair shape for j repetition periods to process the corresponding sub-repair shape.
According to another aspect, a computer program product is presented, comprising instructions which, when executed by a computing device of a device for controlling particle beam induced processing of defects of a microlithographic photomask, prompt the device to perform the method steps according to any of claims 1 to 13.
A computer program product may be provided or supplied such as, for example, a computer program means, e.g. as a storage medium such as a memory card, USB stick, CD-ROM, DVD, or in the form of other files downloadable from a server in a network. For example, in a wireless communication network, this may be accomplished by transmitting appropriate files using a computer program product or computer program means.
Each of the units mentioned above and below, e.g. the computing means, the control means, the determining means, the subdividing means, can be implemented in hardware and/or in software. In the case of a hardware implementation, the corresponding units may be embodied as a device or part of a device, such as a computer or microprocessor. For example, the device may include a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), programmable hardware logic (e.g., a field programmable gate array, FPGA), an Application Specific Integrated Circuit (ASIC), and the like. Furthermore, one or more units may be implemented together in a single hardware device, and they may e.g. share a memory, interface, etc. The units may also be implemented in separate hardware components.
According to another aspect, a method for determining a threshold value is presented. The determined threshold is for subdividing the repair shape into k sub-repair shapes based on the threshold during a particle beam induced processing of a defect of the microlithographic photomask. The method comprises the following steps:
i) Performing particle beam induction treatment on a first test defect of the photomask by using a preset treatment parameter, wherein the first test defect has a first size;
ii) determining the quality of the treatment of the first test defect;
iii) Repeating steps i) and ii) for the modified process parameter until the process parameter is determined, the determined process quality being better than or equal to the predetermined quality;
iv) subjecting the further test defects of the photomask to a particle beam induced process using the determined process parameters, wherein the size of each of the further test defects is different from the size of the other further test defects and from the size of the first test defect;
v) determining the quality of the process for each additional test defect; and
vi) determining a threshold based on the quality determined for the first test defect and the further test defects.
The predetermined and determined processing parameters include, for example, a dwell time of the electron beam on the pixel (e.g., 100ns, 10ns, or a few μs); pause during which no pixels are "exposed" by the electron beam to ensure that there is again sufficient adsorbed process gas (e.g., a value between 100 μs and 5000 μs) at the surface near the repair location; the type of directing (scanning) of the electron beam over the pixels of the repair shape (e.g., line scan, serpentine scan, random targeting over the pixels, and/or incremental targeting over the pixels) and/or the gas volume flow rate of the process gas (e.g., the gas volume flow rate is defined by setting the temperature of the process gas, e.g., between-40 ℃ and +20 ℃).
For example, the quality of the repair is determined by determining the smoothness of the repair location (e.g., the smoothness of the etched or deposited material), the width of the repair edge (e.g., the etched or deposited edge), the repair speed (e.g., the etched or deposited), and/or the etch rate or deposition rate. For example, the predetermined quality is a predetermined value of smoothness of repair locations, width of repair edges, repair speed, etch rate, and/or deposition rate.
Features and advantages described in relation to the method for particle beam induced processing are thus applicable to the apparatus, computer program product and method for determining the threshold value and vice versa.
In the present case, "first; a "is not necessarily to be construed as limited to only one element. Conversely, a plurality of elements, for example, two, three or more, may also be provided. Any other numbers used herein should not be construed as limiting the number of precisely defined elements. Conversely, unless specified to the contrary, numerical deviations upward and downward are possible.
Another possible implementation of the invention also encompasses any combination of features or embodiments not explicitly mentioned above or below with respect to exemplary embodiments. In this case, too, the person skilled in the art will add individual aspects as an improvement or supplement to the corresponding basic form of the invention.
Further advantageous developments and aspects of the invention are the subject matter of the dependent claims, as well as the exemplary embodiments of the invention described below. Hereinafter, the present invention will be explained in more detail based on preferred embodiments with reference to the accompanying drawings.
Drawings
FIG. 1 schematically illustrates details of a microlithography photomask having defects in a structured coating according to one embodiment;
FIG. 2 illustrates an apparatus for particle beam induced processing of defects of the photomask of FIG. 1 according to one embodiment;
FIG. 3 shows another example of a photomask defect of FIG. 1, the geometry of the defect being subdivided into a plurality of sub-repair shapes;
FIG. 4 shows an enlarged detail of FIG. 3;
FIG. 5 shows a view similar to FIG. 3, with the geometry of the defect subdivided into a plurality of sub-repair shapes by two mutually different subdivisions;
FIG. 6 shows another example of a photomask defect of FIG. 1;
FIG. 7 shows another example of a photomask defect of FIG. 1;
FIG. 8 illustrates a flow chart of a method for particle beam induced processing of defects of the photomask of FIG. 1 according to one embodiment;
FIG. 9 shows a flow chart of a method for determining a threshold value, according to one embodiment, in which the threshold value determined in the process can be applied in the method of FIG. 8;
FIG. 10 shows an image of 5 repaired test defects, which were repaired and evaluated in the method of FIG. 9; and
FIG. 11 shows a graph of etch rate as a function of defect size for the test defects of FIG. 10.
Detailed Description
Unless stated to the contrary, identical or functionally identical elements are provided with the same reference numerals in the figures. It should also be understood that the illustrations in the figures are not necessarily drawn to scale.
Fig. 1 schematically shows details of a microlithography photomask 100. In the example shown, photomask 100 is a transmissive lithography mask 100. Photomask 100 includes substrate 102. The substrate 102 is optically transparent, particularly at the wavelength of the exposure photomask 100. For example, the material of the substrate 102 includes fused silica.
A structured coating 104 (pattern element 104) has been applied to the substrate 102. In particular, the coating 104 is a coating made of an absorbent material. For example, the material of the coating 104 includes a chromium layer. For example, the thickness of the coating 104 ranges from 50nm to 100nm. The structural dimension B of the structure formed by the coating 104 on the substrate 102 of the photomask 100 may be different at different locations of the photomask 100. For example, the width B of the region is plotted as the structural dimension in fig. 1. For example, the structure dimension B is located in the region of 20 to 200 nm. The structure dimension B may also be greater than 200nm, for example in the order of micrometers.
In other examples, other materials besides those mentioned may be used for the substrate and the coating. Furthermore, photomask 100 may also be a reflective photomask rather than a transmissive photomask. In this case, a reflective layer is applied instead of the absorptive layer 104.
Sometimes, defect D may occur during production of the photomask, for example, because the etching process does not perform exactly as intended. In fig. 1, such a defect D is indicated by shading. This is an excess of material because coating 104 is not removed from this area, even though two coating areas 104 adjacent to each other are contemplated as being separated in the template of photomask 100. Defect D can also be said to form a web. In this case, the size of the defect D corresponds to the structure size B. Other defects smaller than the structure dimension B, for example of the order of 5 to 20nm, are also known. In order to ensure that structures fabricated in a lithographic apparatus using a photomask have the desired shape on a wafer, the semiconductor assembly produced in this manner thus performs the desired function, requiring repair of defects such as defect D shown in fig. 1 or other defects. In this example, it is necessary to remove the web in a targeted manner, for example by particle beam induced etching.
Fig. 2 shows an apparatus 200 for particle beam induced processing of a defect of a microlithographic photomask, such as defect D of photomask 100 of fig. 1. Fig. 2 shows a schematic cross-section through some components of an apparatus 200, which apparatus 200 may be used for particle beam induced repair of defect D of photomask 100, in this case etching. In addition, apparatus 200 may also be used to image a photomask, and in particular photomask 100, with structured coating 104 of defect D before, during, and after the repair process is performed.
The apparatus 200 shown in fig. 2 represents a modified scanning electron microscope 200. In this case, the defect D is repaired using a particle beam 202 in the form of an electron beam 202. An advantage of using electron beam 202 as an active particle beam is that electron beam 202 does not substantially damage or only slightly damage photomask 100, and in particular substrate 102 thereof.
The laser beam used to activate the localized particle beam induced repair process of photomask 100 may be used instead of electron beam 202 or in addition to electron beam 202 in embodiments (not shown in fig. 2). Furthermore, instead of an electron beam and/or a laser beam, an ion beam, an atomic beam and/or a molecular beam may be used to activate a local chemical reaction (not shown in fig. 2).
The apparatus 200 is mainly arranged in a vacuum housing 204, the vacuum housing 204 being maintained at a certain air pressure by a vacuum pump 206.
For example, apparatus 200 is a repair tool for a microlithographic photomask, such as a photomask for a DUV or EUV lithographic apparatus.
Photomask 100 to be processed is disposed on sample stage 208. For example, sample stage 208 is configured to set the position of photomask 100 in three spatial directions and three rotational axes with an accuracy of a few nanometers.
The device 200 includes an electron column (210). The electron chamber 210 contains an electron source 212 for providing an activating electron beam 202. In addition, the electron chamber 210 contains an electron or beam optics assembly 214. The electron source 212 generates an electron beam 202 and the electron or beam optics 214 focus the electron beam 202 and direct the latter to the photomask 100 at the output of the electron cavity 210. The electron chamber 210 further comprises a deflection unit 216 (scanning unit 216) configured to direct, i.e. scan, the electron beam 202 over the surface of the photomask 100.
Apparatus 200 also includes a detector 218 for detecting secondary and/or backscattered electrons generated at photomask 100 by incident electron beam 202. For example, as shown, the detectors 218 are arranged in an annular fashion around the electron beam 202 within the electron cavity 210. Instead of the detector 218 and/or in addition to the detector 218, the device 200 may also comprise other/further detectors (not shown in fig. 2) for detecting secondary electrons and/or backscattered electrons.
In addition, apparatus 200 may include one or more scanning probe microscopes, such as an atomic force microscope, which may be used to analyze photomask 100 for defects D (not shown in fig. 2).
The apparatus 200 further includes a gas supply unit 220 for supplying a process gas to the surface of the photomask 100. For example, the gas supply unit 220 includes a valve 222 and a gas line 224. The electron beam 202 directed to a position on the surface of the photomask 100 by the electron chamber 210 may perform an Electron Beam Induced Process (EBIP) together with a process gas supplied from the outside by the gas supply unit 220 via the valve 222 and the gas line 224. In particular, the process includes deposition and/or etching of a material.
The apparatus 200 further comprises a computing device 226, such as a computer, having a control means 228, a determining means 230 and a subdividing means 232. In the example of fig. 2, the computing device 226 is disposed outside of the vacuum enclosure 204.
A computing device 226, in particular a control device 228, is used to control the device 200. In particular, the computing means 226, and in particular the control device 228, control the supply of the electron beam 202 by driving the electron chamber 210. In particular, computing device 226, and in particular control device 228, controls the scanning of electron beam 202 across the surface of photomask 100 by driving scanning unit 216. Furthermore, the computing device 226 controls the supply of process gas by driving the gas supply unit 220.
In addition, computing device 226 receives measurement data from detector 218 and/or other detectors of device 200 and generates images from the measurement data, which images may be displayed on a monitor (not shown herein). Furthermore, the images generated from the measurement data may be stored in a memory unit (not shown here) of the computing device 226.
To inspect photomask 100, and in particular structured coating 104 on photomask 100, apparatus 200 is specifically configured to capture image 300 of photomask 100 (FIG. 1) or image 300 of details of photomask 100 from measurement data from detector 218 and/or other detectors of apparatus 200. For example, the spatial resolution of the image 300 is on the order of a few nanometers.
The computing apparatus 226, and in particular the determining device 230, is configured to identify the defect D (fig. 1) in the recorded image 300, to locate the defect and to determine the geometry 302 (repair shape 302) of the defect D. The geometry 302 of the determined defect D, i.e. the repair shape 302, is for example a two-dimensional geometry.
Fig. 3 shows another example of a defect D' of structured coating 104 of photomask 100. In this example, the defect D 'and thus its repair shape 302' is square.
The computing apparatus 226, and in particular the determining device 230, is configured to divide the repair shape 302, 302' (fig. 1 and 3) into a grid containing n pixels 304. Fig. 3 depicts, by way of example, a few pixels 304 of a repair shape 302'. For example, the repair shape 302' includes 100 ten thousand pixels 304 (n= 1 000 000). For example, the side length a (fig. 4) of the pixel 304 is a few nanometers, e.g., 1.5nm. For example, the pixel 304 has a size of 1.5nm by 1.5nm. During the course of the repair method, the electron beam 202 is directed through the scanning unit 216 multiple times toward each center of each pixel 304. In particular, during the process, the intensity maxima of the gaussian intensity distribution of the electron beam 202 are directed multiple times toward each center of each pixel 304.
The computing apparatus 226, in particular the subdivision device 232, is configured to subdivide the repair shape 302, 302' into a plurality, in particular k, of sub-repair shapes 306, for example based on a threshold value W. For example, the computing device 226 is configured to subdivide the repair shape 302, 302' if the number n of pixels 304 of the repair shape exceeds a predetermined threshold W. For example, a particular repair shape 302' is predefined to be subdivided into a total of k sub-repair shapes based on a predetermined threshold W. For example, the predetermined threshold W is an empirically determined threshold W.
In the example shown in fig. 3, the repair shape 302' is subdivided into nine sub-repair shapes 306 (k=9). Each child repair shape 306 has m i A number of pixels 304, which is a subset of the n pixels 304 of the repair shape 302'. In particular, for i=1 to k, m i The sum is equal to n. In the example shown in fig. 3, the sub-repair shapes 306 all have the same dimensions. In other words, each of the nine sub-repair shapes 306 contains the same number m i Pixel 304 (that is m i (i=1 to 9) =n/k). In other examples, m of the ith sub-repair shape 306 i The individual pixels 304 may also differ from one, some or all of the other (k-1) sub-repair shapes 306.
Fig. 4 shows an enlarged detail of fig. 3, wherein five pixels 304 of the first sub-repair shape 306, shown by way of example in fig. 3, are depicted in an enlarged manner. Each pixel 304 is square with a side length a. Thus, the distance M between the centers of two adjacent pixels is also equal to a. A circle of diameter c, represented by reference numeral 308, represents the area of incidence of electron beam 202 on the surface of photomask 100. In this case, the diameter c corresponds to the side length a. The electron beam 202 has, inter alia, a radially symmetric gaussian intensity distribution. In particular, the electron beam 202 is directed towards the center M of the pixel 304 or the incidence area 308 such that the maximum of its intensity distribution is incident on the center M within the technically possible range. For example, the incident area 308 may correspond to the full width at half maximum of the intensity distribution of the electron beam 202. However, the incident area 308 may also correspond to any other intensity drop starting from the maximum of the intensity distribution of the electron beam 202.
For example, the repair shape 302' (fig. 3) is subdivided into k sub-repair shapes 306 by the Voronoi method (Voronoi diagram). In this case, the computing means 226, in particular the subdivision device 232, is used to define the distance s between the Voronoi centers 310 in the repair shape 302' (fig. 3). The Voronoi center (310) in the repair shape 302' is determined based on this distance s using the computing device 226, and in particular the subdivision device 232.
Furthermore, the computing device 226, and in particular the subdivision device 232, is configured in this example to determine the sub-repair shape 306 as a Voronoi region starting from a Voronoi center 310. Thus, each sub-repair shape 306 thus determined includes the pixels 304 of the repair shape 302' corresponding to the associated Voronoi center 310 and all pixels 304 of the repair shape 302' that are disposed closer to the associated Voronoi center 310 than any other Voronoi center 310 of the repair shape 302 '.
Although fig. 3 shows a relatively simple repair shape 302', particularly square, even complex repair shapes may be suitably subdivided into a plurality of sub-repair shapes by the Voronoi method. Examples of this include honeycomb structures or more generally two-dimensional polyhedrons.
The computing device 226, in particular the control means 228, is configured to scan the repair shape 302' which has been subdivided into sub-repair shapes 306 by means of the electron beam 202 and with the supply of process gas, such that a defect D ' which is a geometry of the repair shape 302' is processed and corrected. In this case, the activating electron beam 202 is continuously directed toward m of the first sub-repair shape 306 i＝1 Each of the pixels 304. M of electron beam 202 at first sub-repair shape 306 i＝1 Each of the individual pixels 304 remains at a predetermined dwell time. In this case, m of the first sub-repair shape 306 is repaired by the electron beam 202 i＝1 Each of the individual pixels 304 activates a chemical reaction of the process gas. For example, workersThe process gas comprises an etching gas. For example, the chemical reaction results in a volatile reaction product with the material of the defect D' to be etched, which is at least partially gaseous at room temperature and can be pumped away using a pump system (not shown).
M at which the electron beam 202 is directed toward the first sub-repair shape 306 i＝1 After each of the pixels 304 once (step d)), the procedure is repeated for j repetition periods (step e)).
All m of the first sub-repair shape 306 already in the first sub-repair shape 306 i＝1 After j repetition periods have been processed at the pixels 304, each of the remaining k-1 sub-repair shapes 306 of the repair shape 302' is processed accordingly (step f)). In this case, the order in which the sub-repair shapes 306 are processed may be different from the row-by-row and/or column-by-column order. In other words, in the example of FIG. 3, the sub-repair shapes 306 may also be processed in a different order to proceed sequentially from top left to bottom right. For example, the order in which the sub-repair shapes 306 are processed may be randomly distributed.
In an embodiment, repeating d) to f) over p repetition periods such that m i＝1 The total number of repetition periods for each of the individual pixels 304 is jxp.
To (completely) remove the coating 104 in the region of the defect D', for example, at each pixel m i＝1 A number j (or j x p) of repetition periods is required, amounting to 100, 1000, 10 000, 100 000 or 100 tens of thousands.
Since the repair shape 302 'having n pixels is subdivided into a plurality of sub-repair shapes 306 (k sub-repair shapes 306, in this case nine), each having n/k pixels in the example of fig. 3, the processing time of one of the k sub-repair shapes 306 is shorter than the processing time of the entire repair shape 302'. This is advantageous because the gas composition of the process gas required and/or optimal for treating the defect D' may be better ensured during the treatment of the sub-repair shape 306. For example, the gas composition of the process gas may be updated for each sub-repair shape 306 instead of for each repair shape 302'. This may avoid a significant reduction in etch rate due to, for example, unfavorable gas components of the process gas.
In the case of subdividing 312 the repair shape 302' into the sub-repair shapes 306 shown in fig. 3 and the described scanning method by the electron beam 202, unwanted phenomena may occur in the boundary regions 314 between the sub-repair shapes 306. For example, a boundary region 314 between the first sub-repair shape 306 and the second sub-repair shape 306 has been provided with reference numerals in fig. 3. In such boundary regions 314, the treatment by the electron beam 202 may result in excessive or insufficient material ablation, or excessive or insufficient material deposition.
To avoid such internal repair shape artifacts, the computing device 226, and in particular the subdivision device 232, may be configured to subdivide the repair shape 302' into h mutually different subdivisions 312, 316.
FIG. 5 shows a view similar to FIG. 3, in which the subdivision 312 of the repair shape 302' into the sub-repair shape 306 shown in FIG. 3 is depicted in FIG. 5 using dashed lines. Furthermore, fig. 5 shows a further subdivision 316 calculated by the calculation means 226, in particular the subdivision device 232. Thus, FIG. 5 illustrates the subdivision of the repair shape 302' into two mutually different subdivisions 312, 316.
In the example shown in fig. 5, subdivision 316 differs from subdivision 312 in that boundary 318 of sub-repair shape 306 according to first subdivision 312 is laterally displaced relative to repair shape 302', such that a new sub-repair shape 306' is determined in this manner. As shown in fig. 5, the sub-repair shapes 306' according to the second subdivision 316 have different sizes from each other and different numbers of pixels m ' from each other ' i 。
If multiple subdivisions 312, 316 (h subdivisions, in this case two) are calculated for the repair shape 302' for the purpose of avoiding intra-repair shape artifacts, then, for example, a predetermined number j (or j x p) of repetition cycles is divided between the multiple subdivisions 312, 316. For example, in the example of FIG. 5, each sub-repair shape 306 of the first subdivision 312 and each sub-repair shape 306' of the second subdivision 316 are processed by the electron beam 202 over g repetition periods, where g is equal to j/h (or (j x p)/h) in each case. In other words, the repetition period of a predetermined number j (or j x p) is evenly divided between the two subdivisions 312, 316.
In the case of more complex repair shapes, the computing device 226, and in particular the subdivision device 232, may be configured to perform subdivision of the repair shape while taking into account additional boundary conditions, as illustrated in fig. 6 and 7.
Fig. 6 shows another example of a repair shape 402. The repair shape 402 has a recessed region 404 such that the electron beam 202 of the device 200 will repeatedly pass through a gap 408 present within the recessed region 404 in the scanning direction X. In this case, the computing apparatus 226, and in particular the subdivision device 232, may be configured to subdivide the repair shape 402 into a plurality of sub-repair shapes 406, such that m "of the respective sub-repair shapes 406" i The pixels have the same distance from each other in the scanning direction X. In other words, the repair shape 402 is subdivided into a plurality of sub-repair shapes 406 such that the electron beam 202 does not need to traverse the gap when processing the sub-repair shapes 406 in the scan direction X.
Three pixels 410, 412, 414 of the repair shape 402 are drawn in fig. 6 by way of example. Pixels 410 and 412 belong to a first sub-repair shape 406 and pixel 414 belongs to a second sub-repair shape 406. It is apparent that the two pixels 410 and 412 of the first sub-repair shape 406 are disposed directly adjacent to each other. In particular without gaps therebetween, even in the scanning direction X. In contrast, the first sub-repair shaped pixel 412 and the second sub-repair shaped pixel 414 are not disposed directly adjacent to each other, and there is a distance e therebetween in the scanning direction X, the distance e being a distance corresponding to the gap 408.
Fig. 7 shows another example of a repair shape 502. In this example, the repair shape 502 has two spaced apart regions 504. In other examples, repair shape 502 may also have more than two spaced apart regions 504. To subdivide the repair shape 502, the computing device 226, and in particular the subdivision device 232, may be configured to subdivide the repair shape 502 into a plurality of sub-repair shapes 506 such that each sub-repair shape 506 includes at most one of the two spaced-apart regions 504. In other words, the repair shape 502 is subdivided into a plurality of sub-repair shapes 506 such that the electron beam 202 need not pass through the gap in the scan direction X when processing the sub-repair shapes 506.
FIG. 8 shows a flow chart of a method for particle beam induced processing of microlithographic photomask defects. Defects D, D' of photomask 100 (FIG. 1) may be processed by this method. For example, defect D, D 'has a repair shape 302 as shown in fig. 1, a repair shape 302' as shown in fig. 3, a repair shape 402 as shown in fig. 6, a repair shape 502 as shown in fig. 7, or any other repair shape.
In step S1 of the method, an image 300 of at least a portion of photomask 100 is provided. In particular, a scanning electron microscope image 300 of a portion of photomask 100 is captured by apparatus 200, and defect D, D' of structured coating 104 of photomask 100 is imaged in the image.
In step S2 of the method, the geometry of the defect D, D 'in the image 300 is determined to be the repair shape 302, 302', 402, 502.
In step S3 of the method, the repair shape 302, 302', 402, 502 is subdivided into a plurality of sub-repair shapes 306, 406, 506 in a computer-implemented manner. For example, the subdivision is implemented based on a threshold W (e.g., an empirically determined threshold).
In step S4 of the method, an activating particle beam 202 and a process gas are provided at each pixel of the first sub-repair shape 306, 406, 506.
In step S5 of the method, step S4 is repeated for the first sub-prosthetic shape for j repetition periods.
In step S6 of the method, steps S4 and S5 are repeated for each other of the sub-repair shapes.
In an embodiment, a method for determining the threshold value W is performed, as shown in the flowchart in fig. 9. In particular, the method is performed before the method described above for particle beam induced processing of microlithographic photomask defects (fig. 8). In particular, the method according to fig. 9 is a method of empirically determining the threshold value W.
In the example of the method for determining the threshold value W described with respect to fig. 9, the determinedThe threshold value W is the repair shape size G S (fig. 11), i.e., defect size. In particular, the threshold W in this example has a maximum repair shape size G S . The repair shape size GS may be specified in units of area or the number of pixels.
In other examples, the threshold W may additionally also have a minimum repair shape size. In other words, the threshold W may also exhibit a repair shape size range having a lower limit (minimum repair shape size) and an upper limit (maximum repair shape size).
In other embodiments of the method for determining a threshold value, the threshold value W may also be the repair shape size G S Is a function of the parameters of the model.
The threshold W is determined in the method of fig. 9 such that when the determined threshold W is applied to the repair method of fig. 8, the defect D or D' (fig. 1 or 3) of the photomask 100 may be repaired, e.g., etched, to at least a specified quality by a particle beam induction process. In the method for determining the threshold value W of fig. 9, test defects 602-610 (fig. 10) similar to defects D or D' of photomask 100 of fig. 1 or 3 are repaired by a particle beam induction process for testing purposes, such as using apparatus 200 (fig. 2). The quality of repair is then determined.
For example, the quality of the repair is determined by detecting the smoothness of the etch, the width of the etched edge, and/or the speed of the etch. The quality is dependent on various parameters that can be adjusted by the apparatus 200 (fig. 2), such as the gas volume flow rate (flow rate) of the process gas with respect to the dwell time of the electron beam 202 (fig. 2) on the pixel 304 (fig. 3), the pause between the exposure of the pixel 304 and the further pixel 304, the type of guidance of the electron beam 202 (scanning) on the pixel 304 of the repair shape 302' (e.g. line scan or random aiming on the pixel). In addition, the quality of the repair depends on the type of mask material and the process gas (e.g., process gas mixture) selected for the photomask (e.g., photomask 100 in FIG. 1). Furthermore, the quality of the repair is dependent on the repair shape to be repaired (e.g., repair shapes 302, 302', 402, 502 in fig. 1, 3, 6, 7). In particular, the quality of the repair is dependent on the size of the repair shape (defect size) and, if the repair shape is subdivided into a plurality of sub-repair shapes (e.g., 306 in FIG. 3), also on the size of these sub-repair shapes.
In an example of a method for determining the threshold value W described with respect to fig. 9, for a particular photomask material (e.g., the photomask material of photomask 100 in fig. 1) and a first particular defect size (e.g., the typical or average defect size G) 3 For example 300X 400nm in size 2 ) A first test defect (e.g., test defect 606 in fig. 10) (similar to defect D or D 'of photomask 100 in fig. 1 or 3) is repaired, e.g., etched, by a particle beam induction process using apparatus 200 in step S1'.
In this case, the following repair parameters are set that can be adjusted by the apparatus 200:
i) Dwell time of the electron beam 202 on the pixel (e.g., 100ns, 10ns, or a few μs);
ii) pausing, during which no pixels are "exposed" by the electron beam 202, to ensure that there is again sufficient adsorbed process gas (e.g., a value between 100 μs and 5000 μs) at the surface near the repair location;
iii) The type of directing (scanning) of the electron beam 202 over pixels of the repair shape, such as line scan, serpentine scan, random aiming over pixels, and/or incremental aiming over pixels (e.g., aiming first every x-th pixel, then pixels that have not been "exposed"); and
iv) a gas mass flow rate of the process gas (e.g. the gas mass flow rate is defined by setting a temperature of the process gas, for example between-40 ℃ and +20 ℃).
FIG. 10 shows an image 600 (e.g., SEM image) of a plurality of repaired test defects 602, 604, 606, 608, and 610. Thus, the test defects 602-610 have different sizes G 1 To G 5 . For example, dimension G 1 To G 5 Designated as the number of pixels. For example, dimension G of test defect 602 1 Size G of test defect 604 for 2500 pixels 2 Dimension G of test defect 606 for 40000 pixels 3 Dimension G of test defect 608 is 160000 pixels 4 360000 pixels, and dimension G of test defect 610 5 1000 000 pixels.
However, in other examples, the sizes of the test defects 602-610 may also be assigned to pixels in other units. In addition, the test defects 602-610 may also have a different size G than that specified by way of example 1 To G 5 . Fig. 10 also shows five test defects 602 to 610 by way of example, but may also be applied to cases of more or less than five test defects within the scope of the method for determining the threshold value.
The first test defect repaired (e.g. etched) in step S1' by particle beam induced processing using apparatus 200 for testing purposes is e.g. test defect 606, which has an average size G 3 . However, another one of the test defects 602 to 610 may also be treated as a first test defect in step S1'.
In step S2 'of the method for determining the threshold value W, a repair quality, e.g. etching, of the first test defect 606 processed in step S1' is determined. For example, the quality of the repair is determined by determining the smoothness of the repair location (e.g., the smoothness of the etch), the width of the repair edge (e.g., the etch edge), the speed of the repair (e.g., the etch), and/or the amount of etched or deposited material (e.g., the etch rate or deposition rate).
Fig. 11 shows a graph of etch rate R versus defect size G. For example, for a size G 3 Is determined in step S2' the etching rate R 3 。
In step S3 'of the method for determining the threshold value W, it is determined whether the repair quality of the first test defect 606 determined in step S2' is better than or equal to the prescribed quality. For example, a detected etch rate R of the repaired test defect 606 is determined 3 Whether it is sufficient. For example, a detected etch rate R is determined 3 Whether or not it is greater than a predetermined etching rate R S (FIG. 11).
Steps S1' to S3' are repeatedly performed until the repair quality determined in step S3' is better than or equal to the prescribed quality. In particular, the parameters set in step S2' are changed in the process to determine the optimal parameter settings for the specified quality.
In step S4' of the method for determining the threshold value W, for a series of tests of different defect sizes, for example for test defects 602 to 610, as shown in fig. 10, the size is G 1 To G 5 Is performed using the optimal parameter settings determined in steps S1 'to S3' of the first test defect (e.g., 606, fig. 10). In particular, for defects of a size different from the first prescribed size (e.g. G 3 ) The defect sizes (e.g., G) of the additional test defects 602, 604, 608, and 610 1 、G 2 、G 4 G (G) 5 ) A test series is performed. Within the scope of the test series, the further test defects 602, 604, 608 and 610 are repaired by a particle beam induced process, such as etching.
In step S5' of the method for determining the threshold value W, for each defect size G applied in step S4 1 、G 2 、G 4 G (G) 5 The quality of the repair is determined (i.e., for each of the test defects 602, 604, 608, and 610 repaired in step S4'). For example, an etch rate R is determined for each repaired test defect 602, 604, 608, and 610 1 、R 2 、R 4 R is R 5 (FIG. 11).
As is apparent from fig. 11, for the test defects 602-608 (i.e., defect size G 1 To G 4 ) The determined etching rate R 1 To R 4 Is relatively constant, in particular greater than a predetermined etch rate R S . In other words, the etching process for these test defects 602-608 ends with sufficient results. However, the maximum test defect 610 (defect size G 5 ) Is set to be equal to the etching rate R of 5 Significantly lower than the etch rates of the other test defects 602-608, particularly less than the predetermined etch rate R S . In other words, the etching process of the test defect 610 ends with insufficient results.
In step S6' of the method for determining the threshold value W, the threshold value W is determined based on the results of the test series. For example, the threshold W is based on the maximum defect size (G in fig. 11 4 ) To determine that the quality of repair determined in step S5' is better than or equal toThe specified mass. The threshold value W may also be determined as a defect size range (from the minimum defect size G) where repair quality is better than or equal to the prescribed quality min Up to the maximum defect size G max For example from G in FIG. 11 1 To G 4 )。
For example, the threshold W may also be determined based on the following equation:
W＝{x[(G max ) 0.5 -(Gm in ) 0.5 ]+(Gm in ) 0.5 } 2 。
where x is a coefficient of, for example, 0.5 or 0.75 or 1. In the example of FIG. 11, G max ＝G 4 And G is min ＝G 1 。
In performing the actual photomask repair (fig. 8), the threshold value W determined in the above-described method (fig. 9, steps S1 'to S6') before the actual photomask repair (fig. 8, steps S1 to S6) may be used. In particular, in step c) of the method for particle beam induced processing of defects (fig. 8), when the size of the defect to be processed is greater than a determined threshold W (for example greater than the threshold W determined by the above equation and/or greater than the maximum defect size G still sufficient for repair) max ＝G 4 ) When the repair shape (302, 302' in fig. 1 and 3, respectively) may be subdivided into sub-repair shapes (306 in fig. 3). Furthermore, the k sub-repair shapes (306 in fig. 3) into which the repair shapes (302, 302' in fig. 1, 3) are subdivided in step c) may be set based on the threshold W such that the size of each of the sub-repair shapes (306 in fig. 3) is less than or equal to the determined threshold W and/or the size of each of the sub-repair shapes (306 in fig. 3) is within the determined range of defect sizes.
Although the present invention has been described based on the exemplary embodiments, it may be modified in various ways.
[ list of reference numerals ]
100. Photomask and method for manufacturing the same
102. Substrate and method for manufacturing the same
104. Coating layer
200. Device and method for controlling the same
202. Particle beam
204. Vacuum shell
206. Vacuum pump
208. Sample stage
210. Electronic cavity
212. Electron source
214. Electronic or beam optical component
216. Scanning unit
218. Detector for detecting a target object
220. Gas supply unit
222. Valve
224. Gas pipeline
226. Computing device
228. Control device
230. Determination device
232. Subdivision device
300. Image processing apparatus
302,302' repair shape
304. Pixel arrangement
306. Shape of sub-repair
310 Voronoi center
312. Subdivision
314. Boundary region
316. Subdivision
318. Boundary of
402. Repairing shape
404. Recessed area
406. Shape of sub-repair
408. Gap of
410. Pixel arrangement
412. Pixel arrangement
414. Pixel arrangement
502. Repairing shape
504. Spaced apart regions
506. Shape of sub-repair
600. Image processing apparatus
602. Testing for defects
604. Testing for defects
606. Testing for defects
608. Testing for defects
610. Testing for defects
a pixel size
Width of B structure
c diameter
D, D' defect
e distance
G size
G 1 Size of the device
G 2 Size of the device
G 3 Size of the device
G 4 Size of the device
G 5 Size of the device
G S Size of the device
M center
R etch Rate
R 1 Etching rate
R 2 Etching rate
R 3 Etching rate
R 4 Etching rate
R 5 Etching rate
R S Etching rate
s distance
S1-S6 method steps
S1'-S6' method steps
In the X direction
W threshold
Claims (19)
1. A method for particle beam induced processing of defects (D, D') of a microlithographic photomask (100), comprising the steps of:
a) Providing (S1) an image (300) of at least a portion of the photomask (100);
b) Determining (S2) whether the geometry of the defect (D, D ') in the image (300) is a repair shape (302, 302 '), the repair shape (302, 302 ') comprising n pixels (304);
c) Subdividing (S3) the repair shape (302, 302') into k sub-repair shapes (306) in a computer-implemented manner, an ith one of the k sub-repair shapes (306) having m i -a pixel (304), said m i The number of pixels (304) is n pixels of the repair shape (302, 302') (304) Is a subset of (a);
d) For the purpose of processing a first sub-repair shape (306), at said m of said first sub-repair shape (306) i Providing (S4) an activated particle beam (202) and a process gas at each of the pixels (304);
e) Repeating (S5) step d) for the first sub-repair shape (306) for j repetition periods; and
f) Repeating (S6) steps d) and e) for each additional sub-repair shape (306).
2. The method of claim 1, wherein in step d), only the m of the first sub-repair shape (306) is present i The active particle beam (202) and the process gas are provided at each of the pixels (304).
3. The method according to claim 1 or 2, wherein in step c) the repair shape (302, 302') is subdivided into the k sub-repair shapes (306) based on a threshold value (W).
4. A method according to claim 3, wherein the threshold value (W) is an empirically determined value, which is determined before step a).
5. The method of claim 3 or 4, wherein the particle beam induced processing comprises etching the defect (D, D ') or depositing material on the defect (D, D '), and the threshold value (W) is determined based on empirical values of the etch rate (R) or deposition rate for n pixels (304) of the repair shape (302, 302 ').
6. A method according to any one of claims 3 to 5, wherein the threshold value (W) is an empirically determined value, the value being determined based on a parameter selected from the group comprising: -the n pixels (304) of the repair shape (302, 302'), the size (a) of the pixels (304), -the incidence area (308) of the particle beam (202), -the dwell time of the active particle beam (202) on the respective pixels (304), -the gas volume flow rate at which the process gas is provided, -the composition of the process gas and-the gas volume flow rate ratio of the various gas components of the process gas.
7. The method of any of claims 1 to 6, wherein the repair shape (302, 302') is subdivided into a plurality of sub-repair shapes (306) by means of a Voronoi method.
8. The method of claim 7, wherein in step c) the sub-repair shapes (306) are Voronoi regions determined to start from a Voronoi center (310), each sub-repair shape (306) containing the pixels (304) of the repair shape (302, 302 ') corresponding to the relevant Voronoi center (310) and all pixels (304) of the repair shape (302, 302 ') arranged closer to the relevant Voronoi center (310) configuration than any other Voronoi center (310) of the repair shape (302, 302 ').
9. The method of any of claims 1 to 8, wherein the repair shape (402) is subdivided into the plurality of sub-repair shapes (406) such that m "of the respective sub-repair shapes (406)" i The individual pixels (410, 412) have the same distance from each other in the scanning direction (X).
10. The method of any of claims 1 to 9, wherein the repair shape (502) comprises at least two spaced apart regions (504), and the repair shape (502) is subdivided into the plurality of sub-repair shapes (506) such that each sub-repair shape (506) comprises at most one of the at least two spaced apart regions (504).
11. The method according to any one of claims 1 to 10, wherein the method comprises the following steps before step d): calculating said m at said first sub-repair shape (306) i -providing a sequence of said activated particle beams (202) consecutively at individual pixels (304) such that consumption of said process gas by chemical reactions activated by said activated particle beams (202) is at said sub-The repair shape (306) is uniformly realized.
12. The method according to any one of claims 1 to 11, wherein the order in which steps d) and e) are performed in step f) for the further sub-repair shape (306) is different from a row-by-row and/or column-by-column order and/or a random distribution.
13. The method according to any one of claims 1 to 12, wherein in step c) the repair shape (302, 302 ') is subdivided into sub-repair shapes (306, 306') in h mutually different subdivisions (312, 316), and steps d) to f) are performed for each of the h subdivisions (312, 316).
14. The method of claim 13, wherein steps d) to f) are performed over g repetition periods for each of the h subdivisions (312, 316), wherein g is smaller than j, and/or over j/h repetition periods.
15. The method of claim 13 or 14, wherein the h subdivisions (312, 316) differ from each other by a displacement, in particular a lateral displacement, of a boundary (318) of their sub-repair shape (306) relative to the repair shape (302, 302').
16. The method of any one of claims 1 to 15, wherein steps d) to f) are repeated for p repetition periods, and wherein p is an integer greater than or equal to 2.
17. An apparatus (200) for particle beam induced processing of defects (D, D') of a microlithographic photomask (100), comprising:
a member (210) providing an image (300) of at least a portion of the photomask (100),
-computing means (226) for determining whether a geometry of a defect (D, D ') in the image (300) is a repair shape (302, 302'), the repair shape (302, 302 ') comprising n pixels (304), and the computing means (226) being configured to subdivide the repair shape (302, 302') into a plurality of sub-repair shapes (306) in a computer-implemented manner; and
Means (210, 220) for providing an activating particle beam and a process gas at each pixel (304) of each sub-repair shape (306) for j repetition periods to process the respective sub-repair shape (306).
18. A computer program product comprising instructions which, when executed by a computing device (226) of an apparatus (200) for controlling particle beam induced processing of defects for microlithography photomasks, prompt the apparatus (200) to perform the method steps of any of claims 1 to 16.
19. A method for determining a threshold value (W) for subdividing a repair shape (306) into k sub-repair shapes (306) based on the threshold value (W) during a particle beam induced processing of a defect (D, D') of a microlithographic photomask (100), the method comprising the steps of:
i) Subjecting a first test defect (606) of the photomask (100) to a particle beam induced process (S1') using predetermined process parameters, the first test defect (606) having a first size (G3);
ii) determining (S2') a quality of processing the first test defect (606);
iii) Repeating (S3') steps i) and ii) for the modified process parameter until the process parameter is determined, the determined process quality being superior or equal to the predetermined quality;
iv) subjecting further test defects (602, 604, 608, 610) of the photomask (100) to a particle beam induced process using the determined process parameters, wherein the dimensions (G) of each of the further test defects (602, 604, 608, 610) 1 、G 2 、G 4 、G 5 ) Different from the size (G3) of the other further test defects and from the size (G3) of the first test defect (606);
v) determining (S5') the quality of the process for each further test defect (602, 604, 608, 610); and
vi) determining (S6') the threshold value (W) based on the determined quality for the first test defect and the further test defect (602, 604, 606, 608, 610).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
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| DE102021115736.6 | 2021-06-17 | ||
| DE102021115736.6A DE102021115736B4 (en) | 2021-06-17 | 2021-06-17 | Method and device for particle beam-induced processing of a defect in a photomask for microlithography |
| PCT/EP2022/066347 WO2022263534A1 (en) | 2021-06-17 | 2022-06-15 | Method and apparatus for particle beam-induced processing of a defect of a microlithographic photomask |
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| CN117501178A true CN117501178A (en) | 2024-02-02 |
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| CN202280042961.1A Pending CN117501178A (en) | 2021-06-17 | 2022-06-15 | Method and apparatus for particle beam induced processing of defects in microlithographic photomasks |
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| US (1) | US20240069434A1 (en) |
| EP (1) | EP4356197A1 (en) |
| JP (1) | JP2024522772A (en) |
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| CN (1) | CN117501178A (en) |
| DE (1) | DE102021115736B4 (en) |
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| WO (1) | WO2022263534A1 (en) |
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| WO2000063946A1 (en) * | 1999-04-20 | 2000-10-26 | Seiko Instruments Inc. | Black defect correction method and black defect correction device for photomask |
| DE102008011531B4 (en) | 2008-02-28 | 2011-12-08 | Carl Zeiss Sms Gmbh | Method for processing an object with miniaturized structures |
| JP5693241B2 (en) * | 2008-02-28 | 2015-04-01 | カールツァイス エスエムエス ゲーエムベーハーＣａｒｌ Ｚｅｉｓｓ ＳＭＳ ＧｍｂＨ | Method for processing object having fine structure |
| US9721754B2 (en) | 2011-04-26 | 2017-08-01 | Carl Zeiss Smt Gmbh | Method and apparatus for processing a substrate with a focused particle beam |
| DE102017203879B4 (en) * | 2017-03-09 | 2023-06-07 | Carl Zeiss Smt Gmbh | Method for analyzing a defect site of a photolithographic mask |
| DE102017208114A1 (en) | 2017-05-15 | 2018-05-03 | Carl Zeiss Smt Gmbh | Method and apparatus for particle beam induced etching of a photolithographic mask |
| DE102018209562B3 (en) * | 2018-06-14 | 2019-12-12 | Carl Zeiss Smt Gmbh | Apparatus and methods for inspecting and / or processing an element for photolithography |
| DE102020208185A1 (en) | 2020-06-30 | 2021-12-30 | Carl Zeiss Smt Gmbh | Method and device for setting a side wall angle of a pattern element of a photolithographic mask |
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- 2021-06-17 DE DE102021115736.6A patent/DE102021115736B4/en active Active
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- 2022-06-15 KR KR1020237045106A patent/KR20240011838A/en unknown
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| WO2022263534A1 (en) | 2022-12-22 |
| DE102021115736B4 (en) | 2024-05-29 |
| TW202316196A (en) | 2023-04-16 |
| TWI807864B (en) | 2023-07-01 |
| JP2024522772A (en) | 2024-06-21 |
| EP4356197A1 (en) | 2024-04-24 |
| KR20240011838A (en) | 2024-01-26 |
| DE102021115736A1 (en) | 2022-12-22 |
| US20240069434A1 (en) | 2024-02-29 |
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